Detection of laxative abuse by urine analysis with HPLC and diode array detection.

A simple method is proposed for analysis of stimulant laxatives and metabolites of laxatives in urine. All stimulant laxatives commercially available in Germany, Belgium and the Netherlands, the diphenylmethane derivatives and the anthraquinones, were included. Chromatography was performed with a standardized isocratic HPLC system with diode array detection ('STIP'), which is commonly used in the Netherlands for toxicological screening. The method was validated by ingestion of a normal dose of the laxatives by human volunteers. In all cases the expected laxative metabolite could be detected in urine twelve hours after intake. Also urine samples of patients, suspected of laxative abuse, were analyzed.